This invention relates in general to a computer-input device and in particular to a cursor-pointing device (cursor control stick), of a notebook-type portable computer or similar device.
A finger mouse or cursor control stick, as used in this application, is a man-machine interface device, which controls the motion of a computer display cursor. In particular, a control stick is a type of miniature joystick, which is intended to be operated by the tip of one finger of the user.
Typically, a control stick is mounted in a central location on a computer keyboard, such as between the xe2x80x9cGxe2x80x9d, xe2x80x9cHxe2x80x9d and xe2x80x9cBxe2x80x9d keys on a standard xe2x80x9cQWERTYxe2x80x9d-type keyboard. The control stick has a position sensing mechanism, which detects horizontal pressure in any horizontal direction. The cursor moves in a direction that corresponds to the direction of pressure exerted on the control stick and, in some embodiments, at a speed that corresponds to the amount of pressure exerted on the control stick. The control stick includes an elongated shaft. The shaft of the control stick has a small diameter, thus allowing the control stick to be mounted between the keys of the computer keyboard without causing the placement of the keys to vary greatly from that expected by an experienced user. A cap is typically removably mounted on the upper end of the control stick shaft, in order to provide an enlarged contact surface for a user to press against on the small diameter shaft of the control stick.
Heins, U.S. Pat. No. 6,019,534, discloses a gripping device for a writing instrument with a plurality of annular ribs formed of soft rubber with an internal gel filled chamber. It is known to use a gel material confined in a chamber as is shown in Heins.
Some models of control sticks have a cap with a hard smooth surface, which became slippery during use from perspiration or a build-up of natural body oils. Thus a user has to press their finger with relatively great force against the cap to prevent their finger from slipping on the surface of the cap. The need to press hard on the cap makes control difficult, since the user cannot use the finesse and delicate movements typically needed for rapid, accurate cursor movement. Also, pressing hard on the control stick is physically tiring to the finger, hand and forearm muscles of a user, and causes irritation, inflammation, and bruising of the finger tissue after a period of extended use.
A period of extended use, as used in this application, means a period of use of more than about one hour, and generally more than four hours and less than twelve hours. During such period of use, the user frequently manipulates the control stick. The frequency of manipulation of the control stick during a representative task, such as word processing, will typically be at least every ten minutes, on average, and may be much more frequently, depending on the particular task and the particular user.
Another type of a cap for a control stick has a hard textured outer surface. For example, one known control stick is equipped with a cap which is stippled with bumps which are about the same size and spacing as the abrasive on 150 grit sandpaper. While this approach may help prevent the slipping common with the earliest model cap, the textured cap is still irritating to the finger of a user when used extensively, even with the lighter touch allowed by the textured surface. The uneven and relatively hard surface of such caps still can cause inflamed tissue, bruising, soreness and finger fatigue in users which limits their ability to comfortably use such a control stick for periods of extended use.
The present invention provides a xe2x80x9ccushionedxe2x80x9d cap for a control stick, which cap may suitably be formed from two materials having different durometers (measures of hardness), with a finger contact surface which provides the needed finger-to-cap friction to easily use the control stick to move the cursor with a light touch, and which is formed of a relatively soft material, so that the cap does not irritate the body tissues of the user or result in finger fatigue, even after periods of extended use. A soft texturing may be added to the finger contact surface.